Search

ABSTRACTThe objective of this study was to determine the genetic diversity of multidrug-resistant (MDR) Pseudomonas aeruginosastrains isolated over a period of 12 months in two French hospitals and to test their susceptibility to bacteriophages. A total of 47 MDR isolates recovered from hospitalized patients were genotyped using multiple-locus variable number of tandem repeats analysis. The genotypes were distributed into five clones (including 19, 5, 5, 3, and 3 isolates, respectively) and 12 singletons. Comparison to 77 MDR strains from three other countries, and MLST analysis of selected isolates showed the predominance of international MDR clones. The larger clone, CC235, contained 59 isolates displaying different antibiotic resistance mechanisms, including the presence of the GES1, VIM-2, VIM-4, and IMP-1 β-lactamases. Three newly isolated P. aeruginosabacteriophages were found to lyse 42 of the 44 analyzed strains, distributed into the different clonal complexes. This pilot study suggests that systematic genotyping of P. aeruginosaMDR strains could improve our epidemiological understanding of transmission at both the local (hospital) and the national level and that phage therapy could be an alternative or a complementary treatment to antibiotics for treating MDR-infected patients.

L'antibiogramme sur MGIT (Mycobacterial Growth Indicator Tube) est compare´ a` la me´thode des proportions en milieu solide pour l'e´tude de la sensibilite´ de Mycobacterium tuberculosis a` l'isoniazide (INH), la rifampicine (RIF), la streptomycine (SM) et l'e´thambutol (EMB). Cinquante-quatre souches de M. tuberculosis , dont 30 re´sistantes a` au moins un des quatre antituberculeux cite´s, sont e´tudie´es. Le MGIT est utilise´ selon les recommandations du fabricant : inoculum obtenu a` partir de culture sur Lo¨wenstein-Jensen ; concentrations teste´es pour INH, RIF, SM et EMB respectivement de 0,1 -- 1 -- 0,8 et 3,5 μg/ml ; lecture quotidienne du 3au 14 jour en lumie`re UV a` 365 nm ; sensibilite´ de´finie par l'absence de croissance au plus 48 heures apre`s la positivite´ du tube te´moin. Les tests discordants sont re´pe´te´s. Le de´lai moyen du re´sultat est de 7,9 jours pour l'ensemble des antibiotiques. La contamination est de 0,4 %. La concordance entre les deux techniques est totale pour 48 souches (89 %). La concordance est de 100 % pour INH (23 re´sistantes (R)/31 sensibles [S]) et RIF (3R/51S). Pour SM elle est de 92,6 % (17R/33S), mais quatre isolats re´sistants en me´thode des proportions sont sensibles en MGIT. Pour trois de ces souches, on de´tecte une croissance 24 a` 48 heures apre`s la limite fixe´e par le fabricant. Pour EMB la concordance est de 94,4 % (3R/48S), mais trois isolats re´sistants en me´thode des proportions sont sensibles en MGIT. L'antibiogramme sur MGIT, rapide et concordant avec la me´thode de re´fe´rence, est un comple´ment pour l'e´tude de la sensibilite´ a` INH et RIF. Pour l'e´tude de EMB et SM, les limites de´crites ne sont pas confirme´es par les e´valuations re´centes. Le pyrazinamide ne peut e^tre e´tudie´ actuellement. La sensibilite´ aux contaminations bacte´riennes limite l'usage du MGIT aux laboratoires spe´cialise´s.

ABSTRACTA strain of Nocardiawas isolated from a pulmonary abscess of a human immunodeficiency virus-infected patient in France. Comparative 16S rRNA gene sequence analysis revealed that the isolate represented a strain of Nocardia beijingensis. Antimicrobial susceptibility testing was essential to guide the clinicians to successfully treat this infection.

ABSTRACTMucorales are ubiquitous environmental molds responsible for mucormycosis in diabetic, immunocompromised, and severely burned patients. Small outbreaks of invasive wound mucormycosis (IWM) have already been reported in burn units without extensive microbiological investigations. We faced an outbreak of IWM in our center and investigated the clinical isolates with whole-genome sequencing (WGS) analysis. We analyzed M. circinelloidesisolates from patients in our burn unit (BU1, Hôpital Saint-Louis, Paris, France) together with nonoutbreak isolates from Burn Unit 2 (BU2, Paris area) and from France over a 2-year period (2013 to 2015). A total of 21 isolates, including 14 isolates from six BU1 patients, were analyzed by whole-genome sequencing (WGS). Phylogenetic classification based on de novoassembly and assembly free approaches showed that the clinical isolates clustered in four highly divergent clades. Clade 1 contained at least one of the strains from the six epidemiologically linked BU1 patients. The clinical isolates were specific to each patient. Two patients were infected with more than two strains from different clades, suggesting that an environmental reservoir of clonally unrelated isolates was the source of contamination. Only two patients from BU1 shared one strain, which could correspond to direct transmission or contamination with the same environmental source. In conclusion, WGS of several isolates per patients coupled with precise epidemiological data revealed a complex situation combining potential cross-transmission between patients and multiple contaminations with a heterogeneous pool of strains from a cryptic environmental reservoir.IMPORTANCEInvasive wound mucormycosis (IWM) is a severe infection due to environmental molds belonging to the order Mucorales. Severely burned patients are particularly at risk for IWM. Here, we used whole-genome sequencing (WGS) analysis to resolve an outbreak of IWM due to Mucor circinelloidesthat occurred in our hospital (BU1). We sequenced 21 clinical isolates, including 14 from BU1 and 7 unrelated isolates, and compared them to the reference genome (1006PhL). This analysis revealed that the outbreak was mainly due to multiple strains that seemed patient specific, suggesting that the patients were more likely infected from a pool of diverse strains from the environment rather than from direct transmission among them. This study revealed the complexity of a Mucorales outbreak in the settings of IWM in burn patients, which has been highlighted based on WGS combined with careful sampling.